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  <title>P1831R0: Deprecating &lt;code>volatile&lt;/code>: library</title>
<style data-fill-with="stylesheet">/******************************************************************************
 *                   Style sheet for the W3C specifications                   *
 *
 * Special classes handled by this style sheet include:
 *
 * Indices
 *   - .toc for the Table of Contents (<ol class="toc">)
 *     + <span class="secno"> for the section numbers
 *   - #toc for the Table of Contents (<nav id="toc">)
 *   - ul.index for Indices (<a href="#ref">term</a><span>, in §N.M</span>)
 *   - table.index for Index Tables (e.g. for properties or elements)
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 *     -> use 'scope' attribute, <colgroup>, <thead>, and <tbody> for best results !
 *     -> use <table class='complex data'> for extra-complex tables
 *     -> use <td class='long'> for paragraph-length cell content
 *     -> use <td class='pre'> when manual line breaks/indentation would help readability
 *   - dl.switch for switch statements
 *   - ol.algorithm for algorithms (helps to visualize nesting)
 *   - .figure and .caption (HTML4) and figure and figcaption (HTML5)
 *     -> .sidefigure for right-floated figures
 *   - ins/del
 *
 * Code
 *   - pre and code
 *
 * Special Sections
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 *   - .example    for informative examples          (div, p, pre, span)
 *   - .issue      for issues                        (div, p, span)
 *   - .assertion  for assertions                    (div, p, span)
 *   - .advisement for loud normative statements     (div, p, strong)
 *   - .annoying-warning for spec obsoletion notices (div, aside, details)
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 * Definition Boxes
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 *   - table.def for tables that define other entities (e.g. CSS properties)
 *   - dl.def    for definition lists that define other entitles (e.g. HTML elements)
 *
 * Numbering
 *   - .secno for section numbers in .toc and headings (<span class='secno'>3.2</span>)
 *   - .marker for source-inserted example/figure/issue numbers (<span class='marker'>Issue 4</span>)
 *   - ::before styled for CSS-generated issue/example/figure numbers:
 *     -> Documents wishing to use this only need to add
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 *        .example::before { content: "Example " counter(example) " "; }
 *        .issue::before   { content: "Issue "   counter(issue) " ";   }
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 *   - .copyright for the copyright
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 *     It's better to design things to fit into a narrower measure if possible.
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 *
 ******************************************************************************/

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/******************************************************************************/

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/******************************************************************************/
/*                         Front Matter & Navigation                          */
/******************************************************************************/

/** Header ********************************************************************/

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/** Copyright *****************************************************************/

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/** Back to Top / ToC Toggle **************************************************/

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/******************************************************************************/
/*                                Sectioning                                  */
/******************************************************************************/

/** Headings ******************************************************************/

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/** Subheadings ***************************************************************/

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/******************************************************************************/
/*                            Paragraphs and Lists                            */
/******************************************************************************/

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/** Terminology Markup ********************************************************/


/******************************************************************************/
/*                                 Inline Markup                              */
/******************************************************************************/

/** Terminology Markup ********************************************************/
	dfn   { /* Defining instance */
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	a > i { /* Instance of term */
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	dt dfn code, code.idl {
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	dfn var {
		font-style: normal;
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/** Change Marking ************************************************************/

	del { color: red;  text-decoration: line-through; }
	ins { color: #080; text-decoration: underline;    }

/** Miscellaneous improvements to inline formatting ***************************/

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		vertical-align: super;
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/******************************************************************************/
/*                                    Code                                    */
/******************************************************************************/

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	pre {
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		margin-bottom: 1em;
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/** Inline Code fragments *****************************************************/

  /* Do something nice. */

/******************************************************************************/
/*                                    Links                                   */
/******************************************************************************/

/** General Hyperlinks ********************************************************/

	/* We hyperlink a lot, so make it less intrusive */
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		text-decoration: none;
		border-bottom: 1px solid #707070;
		/* Need a bit of extending for it to look okay */
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	/* Backout above styling for W3C logo */
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		text-decoration: none;
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/******************************************************************************/
/*                                    Images                                  */
/******************************************************************************/

	img {
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	/* For autogen numbers, add
	   .caption::before, figcaption::before { content: "Figure " counter(figure) ". "; }
	*/

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/******************************************************************************/
/*                             Colored Boxes                                  */
/******************************************************************************/

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/** Blockquotes ***************************************************************/

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/** Open issue ****************************************************************/

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/** Example *******************************************************************/

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	/* Add .example::before { content: "Example " counter(example) " "; } for autogen numbers,
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/** Non-normative Note ********************************************************/

	.note {
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	.note::before, .note > .marker,
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		color: hsl(120, 70%, 30%);
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	/* Add .note::before { content: "Note"; } for autogen label,
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		display: block;
		color: hsl(120, 70%, 30%);
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/** Assertion Box *************************************************************/
	/*  for assertions in algorithms */

	.assertion {
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		background: #EEE;
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/** Advisement Box ************************************************************/
	/*  for attention-grabbing normative statements */

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	strong.advisement {
		display: block;
		text-align: center;
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	.advisement > .marker {
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	}

/** Spec Obsoletion Notice ****************************************************/
	/* obnoxious obsoletion notice for older/abandoned specs. */

	details {
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	summary {
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	.annoying-warning:not(details),
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		z-index: 1000;
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}

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/** Entity Definition Boxes ***************************************************/

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		background: #DEF;
		margin: 1.2em 0;
		border-left: 0.5em solid #8CCBF2;
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/******************************************************************************/
/*                                    Tables                                  */
/******************************************************************************/

	th, td {
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		text-align: start;
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/** Property/Descriptor Definition Tables *************************************/

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		border-spacing: 0;
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		vertical-align: baseline;
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	table.def th {
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	/* For when values are extra-complex and need formatting for readability */
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	/* A footnote at the bottom of a def table */
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		display: block;
		height: 0.6em;
		width: 4em;
		border-top: thin solid;
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/** Data tables (and properly marked-up index tables) *************************/
	/*
		 <table class="data"> highlights structural relationships in a table
		 when correct markup is used (e.g. thead/tbody, th vs. td, scope attribute)

		 Use class="complex data" for particularly complicated tables --
		 (This will draw more lines: busier, but clearer.)

		 Use class="long" on table cells with paragraph-like contents
		 (This will adjust text alignment accordingly.)
		 Alternately use class="longlastcol" on tables, to have the last column assume "long".
	*/

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		overflow-wrap: normal;
		hyphens: manual;
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	table.index {
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		border-collapse: collapse;
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		width: 100%;
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		margin: 0 auto 1em;
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		border-width: 1px;
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		border-top-style: solid;
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	table.data  thead,
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 <body class="h-entry">
  <div class="head">
   <p data-fill-with="logo"></p>
   <h1 class="p-name no-ref" id="title">P1831R0<br>Deprecating <code class="highlight"><c- k>volatile</c-></code>: library</h1>
   <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Published Proposal, <time class="dt-updated" datetime="1970-01-01">1970-01-01</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt>This version:
     <dd><a class="u-url" href="http://wg21.link/P1831R0">http://wg21.link/P1831R0</a>
     <dt>Author:
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:jfbastien@apple.com">JF Bastien</a> (<span class="p-org org">Apple</span>)
     <dt>Audience:
     <dd>LWG
     <dt>Project:
     <dd>ISO/IEC JTC1/SC22/WG21 14882: Programming Language — C++
     <dt>Source:
     <dd><a href="https://github.com/jfbastien/papers/blob/master/source/P1831R0.bs">github.com/jfbastien/papers/blob/master/source/P1831R0.bs</a>
    </dl>
   </div>
   <div data-fill-with="warning"></div>
   <hr title="Separator for header">
  </div>
  <nav data-fill-with="table-of-contents" id="toc">
   <h2 class="no-num no-toc no-ref" id="contents">Table of Contents</h2>
   <ol class="toc" role="directory">
    <li><a href="#abstract"><span class="secno">1</span> <span class="content">Abstract</span></a>
    <li>
     <a href="#word"><span class="secno">2</span> <span class="content">Wording</span></a>
     <ol class="toc">
      <li><a href="#tuple"><span class="secno">2.1</span> <span class="content">Tuples [<strong>tuple</strong>]</span></a>
      <li><a href="#variant"><span class="secno">2.2</span> <span class="content">Variants [<strong>variant</strong>]</span></a>
      <li><a href="#atomics"><span class="secno">2.3</span> <span class="content">Atomic operations library [<strong>atomics</strong>]</span></a>
      <li>
       <a href="#annexD"><span class="secno">2.4</span> <span class="content">Annex D</span></a>
       <ol class="toc">
        <li><a href="#depr.tuple"><span class="secno">2.4.1</span> <span class="content">Tuple [<strong>depr.tuple</strong>]</span></a>
        <li><a href="#depr.variant"><span class="secno">2.4.2</span> <span class="content">Variant [<strong>depr.variant</strong>]</span></a>
        <li><a href="#depr.atomics"><span class="secno">2.4.3</span> <span class="content">Atomic operations library [<strong>depr.atomics</strong>]</span></a>
       </ol>
     </ol>
    <li>
     <a href="#references"><span class="secno"></span> <span class="content">References</span></a>
     <ol class="toc">
      <li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
     </ol>
   </ol>
  </nav>
  <main>
   <h2 class="heading settled" data-level="1" id="abstract"><span class="secno">1. </span><span class="content">Abstract</span><a class="self-link" href="#abstract"></a></h2>
   <p>This paper is the library part of P1152. The Core language parts of the
deprecation were voted into C++20 at the Cologne meeting as <a data-link-type="biblio" href="#biblio-p1152r4">[P1152R4]</a>. LWG was
unable to review library wording, this paper therefore carries forward the
library parts of <span>[P1152R3]</span>.</p>
   <h2 class="heading settled" data-level="2" id="word"><span class="secno">2. </span><span class="content">Wording</span><a class="self-link" href="#word"></a></h2>
   <p>The proposed wording follows the library approach to deprecation: library
deprecation presents the library without the deprecated feature, and only
mentions said feature in Annex D.</p>
   <h3 class="heading settled" data-level="2.1" id="tuple"><span class="secno">2.1. </span><span class="content">Tuples [<strong>tuple</strong>]</span><a class="self-link" href="#tuple"></a></h3>
   <p>Modify as follows.</p>
   <blockquote>
    <p>Header <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> synopsis [<strong>tuple.syn</strong>]:</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>std</c-></c-> <c- p><c- p>{</c-></c->
    
<c- p><c- p>[...]</c-></c->
    
<c- c1><c- c1>// [</c-></c-><i><c- c1><c- c1>tuple.helper</c-></c-></i><c- c1><c- c1>], tuple helper classes</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- p><c- p>;</c-></c->                  <c- c1><c- c1>// not defined</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
    
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>class</c-></c-><c- p><c- p>...</c-></c-> <c- n><c- n>Types</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>tuple</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>Types</c-></c-><c- p><c- p>...</c-></c-><c- o><c- o>>></c-></c-><c- p><c- p>;</c-></c->
    
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- p><c- p>;</c-></c->     <c- c1><c- c1>// not defined</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>

<c- p><c- p>[...]</c-></c->
    
<c- p><c- p>}</c-></c->
    
</code></pre>
    <p>[...]</p>
    <p>Tuple helper classes [<strong>tuple.helper</strong>]</p>
<pre class="highlight"><code class="highlight"> <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
 <del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
</del> <del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
</del></code></pre>
    <p>
     Let <code class="highlight"><c- n>TS</c-></code> denote <code class="highlight"><c- n>tuple_size</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>. If the
  expression <code class="highlight"><c- n>TS</c-><c- o>::</c-><c- n>value</c-></code> is well-formed when treated as an unevaluated operand,
  then 
     <del>each of the three templates</del>
     <ins>the template</ins>
      shall satisfy the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements with a base characteristic of
    </p>
<pre class="highlight"><code class="highlight"><c- n><c- n>integral_constant</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>TS</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>value</c-></c-><c- o><c- o>></c-></c-></code></pre>
    <p>Otherwise, they shall have no member <code class="highlight"><c- n>value</c-></code>.</p>
    <p>Access checking is performed as if in a context unrelated to <code class="highlight"><c- n>TS</c-></code> and <code class="highlight"><c- n>T</c-></code>.
  Only the validity of the immediate context of the expression is considered. [ <em>Note:</em> The compilation of the expression can result in side effects such as
  the instantiation of class template specializations and function template
  specializations, the generation of implicitly-defined functions, and so on.
  Such side effects are not in the "immediate context" and can result in the
  program being ill-formed. —<em>end note</em> ]</p>
    <p>
     In addition to being available via inclusion of the <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> header,
  the 
     <del>three templates are</del>
     <ins>template is</ins>
      available when any of the
  headers <code class="highlight"><c- o>&lt;</c-><c- n>array</c-><c- o>></c-></code>, <code class="highlight"><c- o>&lt;</c-><c- n>ranges</c-><c- o>></c-></code>, or <code class="highlight"><c- o>&lt;</c-><c- n>utility</c-><c- o>></c-></code> are included.
    </p>
<pre class="highlight"><code class="highlight">  
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
</code></pre>
    <p>
     Let <code class="highlight"><c- n>TE</c-></code> denote <code class="highlight"><c- n>tuple_element_t</c-><c- o>&lt;</c-><c- n>I</c-><c- p>,</c-> <c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>.
  Then 
     <del>each of the three templates</del>
     <ins>the template</ins>
      shall satisfy
  the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements with a member typedef <code class="highlight"><c- n>type</c-></code> that names
  the 
     <del>following </del>
     type
     <del>:</del>
     <ins> <code class="highlight"><c- n>add_const_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>.</ins>
    </p>
    <del>
     <ul>
      <li>for the first specialization, <code class="highlight"><c- n>add_const_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>, 
      <li>for the second specialization, <code class="highlight"><c- n>add_volatile_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>, and 
      <li>for the third specialization, <code class="highlight"><c- n>add_cv_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>. 
     </ul>
    </del>
    <p>
     In addition to being available via inclusion of the <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> header,
  the 
     <del>three templates are</del>
     <ins>template is</ins>
      available when any of the
  headers <code class="highlight"><c- o>&lt;</c-><c- n>array</c-><c- o>></c-></code>, <code class="highlight"><c- o>&lt;</c-><c- n>ranges</c-><c- o>></c-></code>, or <code class="highlight"><c- o>&lt;</c-><c- n>utility</c-><c- o>></c-></code> are included.
    </p>
   </blockquote>
   <h3 class="heading settled" data-level="2.2" id="variant"><span class="secno">2.2. </span><span class="content">Variants [<strong>variant</strong>]</span><a class="self-link" href="#variant"></a></h3>
   <p>Modify as follows.</p>
   <blockquote>
    <p><code class="highlight"><c- o>&lt;</c-><c- n>variant</c-><c- o>></c-></code> synopsis [<strong>variant.syn</strong>]</p>
<pre class="highlight"><code class="highlight">  
<c- k><c- k>namespace</c-></c-> <c- n><c- n>std</c-></c-> <c- p><c- p>{</c-></c->
<c- c1><c- c1>// [</c-></c-><i><c- c1><c- c1>variant.variant</c-></c-></i><c- c1><c- c1>], class template variant</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>class</c-></c-><c- p><c- p>...</c-></c-> <c- n><c- n>Types</c-></c-><c- o><c- o>></c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant</c-></c-><c- p><c- p>;</c-></c->

<c- c1><c- c1>// [</c-></c-><i><c- c1><c- c1>variant.helper</c-></c-></i><c- c1><c- c1>], variant helper classes</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- p><c- p>;</c-></c->                   <c- c1><c- c1>// not defined</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c->
  <c- kr><c- kr>inline</c-></c-> <c- k><c- k>constexpr</c-></c-> <c- b><c- b>size_t</c-></c-> <c- n><c- n>variant_size_v</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>value</c-></c-><c- p><c- p>;</c-></c->

<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>class</c-></c-><c- p><c- p>...</c-></c-> <c- n><c- n>Types</c-></c-><c- o><c- o>></c-></c->
  <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>variant</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>Types</c-></c-><c- p><c- p>...</c-></c-><c- o><c- o>>></c-></c-><c- p><c- p>;</c-></c->

<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- p><c- p>;</c-></c->  <c- c1><c- c1>// not defined</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>

<c- p><c- p>[...]</c-></c->
  
<c- p><c- p>}</c-></c->
  
</code></pre>
    <p><code class="highlight"><c- n>variant</c-></code> helper classes [<strong>variant.helper</strong>]</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- p><c- p>;</c-></c-></code></pre>
    <p><em>Remark:</em> All specializations of <code class="highlight"><c- n>variant_size</c-></code> shall satisfy the <code class="highlight"><c- n>UnaryTypeTrait</c-></code> requirements with a base characteristic of <code class="highlight"><c- n>integral_constant</c-><c- o>&lt;</c-><c- b>size_t</c-><c- p>,</c-> <c- n>N</c-><c- o>></c-></code> for some <code class="highlight"><c- n>N</c-></code>.</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c-> <c- k>class</c-> <c- nc>variant_size</c-><c- o>&lt;</c-><c- k>const</c-> <c- n>T</c-><c- o>></c-><c- p>;</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c-> <c- k>class</c-> <c- nc>variant_size</c-><c- o>&lt;</c-><c- k>volatile</c-> <c- n>T</c-><c- o>></c-><c- p>;</c-></del>
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c-> <c- k>class</c-> <c- nc>variant_size</c-><c- o>&lt;</c-><c- k>const</c-> <c- k>volatile</c-> <c- n>T</c-><c- o>></c-><c- p>;</c-></del>
</pre>
    <p>
     Let <code class="highlight"><c- n>VS</c-></code> denote <code class="highlight"><c- n>variant_size</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>. Then 
     <del>each
  of the three templates</del>
     <ins>the template</ins>
      shall satisfy the <code class="highlight"><c- n>UnaryTypeTrait</c-></code> requirements with a
  base characteristic of <code class="highlight"><c- n>integral_constant</c-><c- o>&lt;</c-><c- b>size_t</c-><c- p>,</c-> <c- n>VS</c-><c- o>::</c-><c- n>value</c-><c- o>></c-></code>.
    </p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>class</c-></c-><c- p><c- p>...</c-></c-> <c- n><c- n>Types</c-></c-><c- o><c- o>></c-></c->
  <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>variant</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>Types</c-></c-><c- p><c- p>...</c-></c-><c- o><c- o>>></c-></c-> <c- o><c- o>:</c-></c-> <c- n><c- n>integral_constant</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>sizeof</c-></c-><c- p><c- p>...(</c-></c-><c- n><c- n>Types</c-></c-><c- p><c- p>)</c-></c-><c- o><c- o>></c-></c-> <c- p><c- p>{</c-></c-> <c- p><c- p>};</c-></c->
</code></pre>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
<del><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c-></del>
</code></pre>
    <p>
     Let <code class="highlight"><c- n>VA</c-></code> denote <code class="highlight"><c- n>variant_alternative</c-><c- o>&lt;</c-><c- n>I</c-><c- p>,</c-> <c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>.
  Then 
     <del>each of the three templates</del>
     <ins>the template</ins>
      shall meet the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements with a member typedef <code class="highlight"><c- n>type</c-></code> that names the 
     <del>following</del>
      type
     <del>:</del>
     <ins> <code class="highlight"><c- n>add_const_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>.</ins>
    </p>
    <del>
     <ul>
      <li>for the first specialization, <code class="highlight"><c- n>add_const_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>, 
      <li>for the second specialization, <code class="highlight"><c- n>add_volatile_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>, and 
      <li>for the third specialization, <code class="highlight"><c- n>add_cv_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>. 
     </ul>
    </del>
   </blockquote>
   <h3 class="heading settled" data-level="2.3" id="atomics"><span class="secno">2.3. </span><span class="content">Atomic operations library [<strong>atomics</strong>]</span><a class="self-link" href="#atomics"></a></h3>
   <p>Modify as follows.</p>
   <blockquote>
    <p>Operations on atomic types [<strong>atomics.types.operations</strong>]</p>
    <p>[ <em>Note:</em> Many operations are <code class="highlight"><c- k>volatile</c-></code>-qualified. The "volatile as device
  register" semantics have not changed in the standard. This qualification means
  that volatility is preserved when applying these operations to volatile
  objects. It does not mean that operations on non-volatile objects become
  volatile. —<em>end note</em> ]</p>
    <p>[...]</p>
<pre class="highlight"><code class="highlight"><c- b><c- b>bool</c-></c-> <c- nf><c- nf>is_lock_free</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>is_lock_free</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <p><em>Returns:</em> <code class="highlight">true</code> if the object’s operations are lock-free, <code class="highlight">false</code> otherwise.</p>
    <p>[ <em>Note:</em> The return value of the <code class="highlight"><c- n>is_lock_free</c-></code> member function is consistent with the value of <code class="highlight"><c- n>is_always_lock_free</c-></code> for the same type. —<em>end note</em> ]</p>
<pre class="highlight"><code class="highlight"><c- b><c- b>void</c-></c-> <c- nf><c- nf>store</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>void</c-></c-> <c- nf><c- nf>store</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <p><em>Requires:</em> The <code class="highlight"><c- n>order</c-></code> argument shall not be <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>consume</c-></code>, <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acquire</c-></code>, nor <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acq_rel</c-></code>.</p>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Atomically replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with the value of <code class="highlight"><c- n>desired</c-></code>. Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>.</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to <code class="highlight"><c- n>store</c-><c- p>(</c-><c- n>desired</c-><c- p>)</c-></code>.</p>
    <p><em>Returns:</em> <code class="highlight"><c- n>desired</c-></code>.</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- nf><c- nf>load</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>load</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <p><em>Requires:</em> The <code class="highlight"><c- n>order</c-></code> argument shall not be <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>release</c-></code> nor <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acq_rel</c-></code>.</p>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>.</p>
    <p><em>Returns:</em> Atomically returns the value pointed to by <code class="highlight"><c- k>this</c-></code>.</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>operator</c-></c-> <c- nf><c- nf>T</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>operator</c-></c-> <c- nf><c- nf>T</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>load</c-><c- p>();</c-></code></p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- nf><c- nf>exchange</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>exchange</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Atomically replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with <code class="highlight"><c- n>desired</c-></code>. Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>. These operations are atomic read-modify-write operations.</p>
    <p><em>Returns:</em> Atomically returns the value pointed to by <code class="highlight"><c- k>this</c-></code> immediately before the effects.</p>
<pre class="highlight"><code class="highlight"><c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                           <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                           <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                             <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                             <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                           <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                           <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                             <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c->
                             <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <p><em>Requires:</em> The <code class="highlight"><c- n>failure</c-></code> argument shall not be <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>release</c-></code> nor <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acq_rel</c-></code>.</p>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Retrieves the value in <code class="highlight"><c- n>expected</c-></code>. It then atomically compares the value representation of the value pointed to by <code class="highlight"><c- k>this</c-></code> for equality with that previously retrieved from <code class="highlight"><c- n>expected</c-></code>,eand if true, replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with that in <code class="highlight"><c- n>desired</c-></code>. If and only if the comparison is true, memory is affected according to the value of <code class="highlight"><c- n>success</c-></code>, and if the comparison is false, memory is affected according to the value of <code class="highlight"><c- n>failure</c-></code>. When only one <code class="highlight"><c- n>memory_order</c-></code> argument is supplied, the value of <code class="highlight"><c- n>success</c-></code> is <code class="highlight"><c- n>order</c-></code>, and the value of <code class="highlight"><c- n>failure</c-></code> is <code class="highlight"><c- n>order</c-></code> except that a value of <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acq_rel</c-></code> shall be replaced by the value <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>acquire</c-></code> and a value of <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>release</c-></code> shall be replaced by the value <code class="highlight"><c- n>memory_order</c-><c- o>::</c-><c- n>relaxed</c-></code>. If and only if the comparison is false then, after the atomic operation, the value in <code class="highlight"><c- n>expected</c-></code> is replaced by the value pointed to by <code class="highlight"><c- k>this</c-></code> during the atomic comparison. If the operation returns <code class="highlight">true</code>, these operations are atomic read-modify-write operations on the memory pointed to by <code class="highlight"><c- k>this</c-></code>. Otherwise, these operations are atomic load operations on that memory.</p>
    <p><em>Returns:</em> The result of the comparison.</p>
    <p>[...]</p>
    <p>Specializations for integers [<strong>atomics.types.int</strong>]</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Atomically replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with the result of the computation applied to the value pointed to by <code class="highlight"><c- k>this</c-></code> and the given <code class="highlight"><c- n>operand</c-></code>. Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>. These operations are atomic read-modify-write operations.</p>
    <p><em>Returns:</em> Atomically, the value pointed to by <code class="highlight"><c- k>this</c-></code> immediately before the effects.</p>
    <p><em>Remarks:</em> For signed integer types, the result is as if the object value and parameters were converted to their corresponding unsigned types, the computation performed on those types, and the result converted back to the signed type. [ <em>Note:</em> There are no undefined results arising from the computation.  —<em>end note</em> ]</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_</c-><i><c- nf>key</c-></i><c- p>(</c-><c- n>operand</c-><c- p>)</c-> <i><c- n>op</c-></i> <c- n>operand</c-><c- p>;</c-></code></p>
    <p>Specializations for floating-point types [<strong>atomics.types.float</strong>]</p>
    <p>The following operations perform arithmetic addition and subtraction computations. The key, operator, and computation correspondence are identified in [<strong>atomic.arithmetic.computations</strong>].</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- n><c- n>A</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>fetch_</c-></c-><i><c- n><c- n>key</c-></c-></i><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order_seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- n><c- n>A</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>fetch_</c-></c-><i><c- n><c- n>key</c-></c-></i><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order_seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Atomically replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with the result of the computation applied to the value pointed to by <code class="highlight"><c- k>this</c-></code> and the given <code class="highlight"><c- n>operand</c-></code>. Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>. These operations are atomic read-modify-write operations.</p>
    <p><em>Returns:</em> Atomically, the value pointed to by <code class="highlight"><c- k>this</c-></code> immediately before the effects.</p>
    <p><em>Remarks:</em> If the result is not a representable value for its type the result is unspecified, but the operations otherwise have no undefined behavior. Atomic arithmetic operations on <code class="highlight"><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i></code> should conform to the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>numeric_limits</c-><c- o>&lt;</c-><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i><c- o>></c-></code> traits associated with the floating-point type. The floating-point environment for atomic arithmetic operations on <code class="highlight"><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i></code> may be different than the calling thread’s floating-point environment.</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_</c-><i><c- nf>key</c-></i><c- p>(</c-><c- n>operand</c-><c- p>)</c-> <i><c- n>op</c-></i> <c- n>operand</c-><c- p>;</c-></code></p>
    <p><em>Remarks:</em> If the result is not a representable value for its type the result is unspecified, but the operations otherwise have no undefined behavior. Atomic arithmetic operations on <code class="highlight"><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i></code> should conform to the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>numeric_limits</c-><c- o>&lt;</c-><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i><c- o>></c-></code> traits associated with the floating-point type. The floating-point environment for atomic arithmetic operations on <code class="highlight"><i><c- n>floating</c-><c- o>-</c-><c- n>point</c-></i></code> may be different than the calling thread’s floating-point environment.</p>
    <p>Partial specialization for pointers [<strong>atomics.types.pointer</strong>]</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-><c- o><c- o>*</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- b><c- b>ptrdiff_t</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-><c- o><c- o>*</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- b><c- b>ptrdiff_t</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <p><em>Requires:</em> T shall be an object type, otherwise the program is ill-formed. [ <em>Note:</em> Pointer arithmetic on <code class="highlight"><c- b>void</c-><c- o>*</c-></code> or function pointers is ill-formed. —<em>end note</em> ]</p>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Atomically replaces the value pointed to by <code class="highlight"><c- k>this</c-></code> with the result of the computation applied to the value pointed to by <code class="highlight"><c- k>this</c-></code> and the given <code class="highlight"><c- n>operand</c-></code>. Memory is affected according to the value of <code class="highlight"><c- n>order</c-></code>. These operations are atomic read-modify-write operations.</p>
    <p><em>Returns:</em> Atomically, the value pointed to by <code class="highlight"><c- k>this</c-></code> immediately before the effects.</p>
    <p><em>Remarks:</em> The result may be an undefined address, but the operations otherwise have no undefined behavior.</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-><c- o><c- o>*</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>ptrdiff_t</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-><c- o><c- o>*</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>ptrdiff_t</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overloads of these functions, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_</c-><i><c- nf>key</c-></i><c- p>(</c-><c- n>operand</c-><c- p>)</c-> <i><c- n>op</c-></i> <c- n>operand</c-><c- p>;</c-></code></p>
    <p>Member operators common to integers and pointers to objects [<strong>atomics.types.memop</strong>]</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>++</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>++</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_add</c-><c- p>(</c-><c- mi>1</c-><c- p>);</c-></code></p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>--</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>--</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_sub</c-><c- p>(</c-><c- mi>1</c-><c- p>);</c-></code></p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>++</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>++</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_add</c-><c- p>(</c-><c- mi>1</c-><c- p>)</c-> <c- o>+</c-> <c- mi>1</c-><c- p>;</c-></code></p>
<pre class="highlight"><code class="highlight"><c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>--</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>--</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Equivalent to: <code class="highlight"><c- k>return</c-> <c- nf>fetch_sub</c-><c- p>(</c-><c- mi>1</c-><c- p>)</c-> <c- o>-</c-> <c- mi>1</c-><c- p>;</c-></code></p>
    <p>Non-member functions [<strong>atomics.nonmembers</strong>]</p>
    <p>A non-member function template whose name matches the pattern <code class="highlight"><c- n>atomic_</c-><i><c- n>f</c-></i></code> or the pattern <code class="highlight"><c- n>atomic_</c-><i><c- n>f</c-></i><c- n>_explicit</c-></code> invokes the member function <code class="highlight"><i><c- n>f</c-></i></code>, with the value of the first parameter as the object expression and the values of the remaining parameters (if any) as the arguments of the member function call, in order. An argument for a parameter of type <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>value_type</c-><c- o>*</c-></code> is dereferenced when passed to the member function call. If no such member function exists, the program is ill-formed.</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>atomic_init</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>*</c-></c-> <c- n><c- n>object</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>value_type</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>atomic_init</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>*</c-></c-> <c- n><c- n>object</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>value_type</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
    <ins><em>Mandates:</em> For the <code class="highlight"><c- k>volatile</c-></code> overload of this function, <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">true</code>.</ins>
    <p><em>Effects:</em> Non-atomically initializes <code class="highlight"><c- o>*</c-><c- n>object</c-></code> with value <code class="highlight"><c- n>desired</c-></code>. This function shall only be applied to objects that have been default constructed, and then only once. [ <em>Note:</em> These semantics ensure compatibility with C. —<em>end note</em> ] [ <em>Note:</em> Concurrent access from another thread, even via an atomic operation, constitutes a data race.  —<em>end note</em> ]</p>
    <p>[ <em>Note:</em> The non-member functions enable programmers to write code that can be compiled as either C or C++, for example in a shared header file.  —<em>end note</em> ]</p>
   </blockquote>
   <h3 class="heading settled" data-level="2.4" id="annexD"><span class="secno">2.4. </span><span class="content">Annex D</span><a class="self-link" href="#annexD"></a></h3>
   <p>Add the following wording to Annex D:</p>
   <h4 class="heading settled" data-level="2.4.1" id="depr.tuple"><span class="secno">2.4.1. </span><span class="content">Tuple [<strong>depr.tuple</strong>]</span><a class="self-link" href="#depr.tuple"></a></h4>
   <p>Header <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> synopsis [<strong>depr.tuple.syn</strong>]:</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>std</c-></c-> <c- p><c- p>{</c-></c->
    
<c- p><c- p>[...]</c-></c->
    
<c- c1><c- c1>// [</c-></c-><i><c- c1><c- c1>tuple.helper</c-></c-></i><c- c1><c- c1>], tuple helper classes</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
    
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->

<c- p><c- p>[...]</c-></c->
    
<c- p><c- p>}</c-></c->
    
</code></pre>
   <p>Tuple helper classes [<strong>depr.tuple.helper</strong>]</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
</code></pre>
   <p>Let <code class="highlight"><c- n>TS</c-></code> denote <code class="highlight"><c- n>tuple_size</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>. If the
  expression <code class="highlight"><c- n>TS</c-><c- o>::</c-><c- n>value</c-></code> is well-formed when treated as an unevaluated operand,
  then each of the two templates shall satisfy the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements with a base characteristic of</p>
<pre class="highlight"><code class="highlight"><c- n><c- n>integral_constant</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>TS</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>value</c-></c-><c- o><c- o>></c-></c-></code></pre>
   <p>Otherwise, they shall have no member <code class="highlight"><c- n>value</c-></code>.</p>
   <p>Access checking is performed as if in a context unrelated to <code class="highlight"><c- n>TS</c-></code> and <code class="highlight"><c- n>T</c-></code>.
  Only the validity of the immediate context of the expression is considered.</p>
   <p>In addition to being available via inclusion of the <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> header, the two
  templates are available when any of the headers <code class="highlight"><c- o>&lt;</c-><c- n>array</c-><c- o>></c-></code>, <code class="highlight"><c- o>&lt;</c-><c- n>ranges</c-><c- o>></c-></code>, or <code class="highlight"><c- o>&lt;</c-><c- n>utility</c-><c- o>></c-></code> are included.</p>
<pre class="highlight"><code class="highlight">  
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>tuple_element</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
</code></pre>
   <p>Let <code class="highlight"><c- n>TE</c-></code> denote <code class="highlight"><c- n>tuple_element_t</c-><c- o>&lt;</c-><c- n>I</c-><c- p>,</c-> <c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>. Then
  each of the two templates shall satisfy the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements
  with a member typedef <code class="highlight"><c- n>type</c-></code> that names the following type:</p>
   <ul>
    <li>for the first specialization, <code class="highlight"><c- n>add_volatile_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>, and 
    <li>for the second specialization, <code class="highlight"><c- n>add_cv_t</c-><c- o>&lt;</c-><c- n>TE</c-><c- o>></c-></code>. 
   </ul>
   <p>In addition to being available via inclusion of the <code class="highlight"><c- o>&lt;</c-><c- n>tuple</c-><c- o>></c-></code> header, the two
  templates are available when any of the headers <code class="highlight"><c- o>&lt;</c-><c- n>array</c-><c- o>></c-></code>, <code class="highlight"><c- o>&lt;</c-><c- n>ranges</c-><c- o>></c-></code>, or <code class="highlight"><c- o>&lt;</c-><c- n>utility</c-><c- o>></c-></code> are included.</p>
   <h4 class="heading settled" data-level="2.4.2" id="depr.variant"><span class="secno">2.4.2. </span><span class="content">Variant [<strong>depr.variant</strong>]</span><a class="self-link" href="#depr.variant"></a></h4>
   <p><code class="highlight"><c- o>&lt;</c-><c- n>variant</c-><c- o>></c-></code> synopsis [<strong>depr.variant.syn</strong>]</p>
<pre class="highlight"><code class="highlight">  
<c- k><c- k>namespace</c-></c-> <c- n><c- n>std</c-></c-> <c- p><c- p>{</c-></c->

<c- c1><c- c1>// [</c-></c-><i><c- c1><c- c1>variant.helper</c-></c-></i><c- c1><c- c1>], variant helper classes</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_size</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->

<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>struct</c-></c-> <c- n><c- n>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
  
<c- p><c- p>}</c-></c->
  
</code></pre>
   <p><code class="highlight"><c- n>variant</c-></code> helper classes [<strong>depr.variant.helper</strong>]</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c-> <c- k>class</c-> <c- nc>variant_size</c-><c- o>&lt;</c-><c- k>volatile</c-> <c- n>T</c-><c- o>></c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c-> <c- k>class</c-> <c- nc>variant_size</c-><c- o>&lt;</c-><c- k>const</c-> <c- k>volatile</c-> <c- n>T</c-><c- o>></c-><c- p>;</c->
</pre>
   <p>Let <code class="highlight"><c- n>VS</c-></code> denote <code class="highlight"><c- n>variant_size</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>. Then each
  of the two templates shall satisfy the <code class="highlight"><c- n>UnaryTypeTrait</c-></code> requirements with a
  base characteristic of <code class="highlight"><c- n>integral_constant</c-><c- o>&lt;</c-><c- b>size_t</c-><c- p>,</c-> <c- n>VS</c-><c- o>::</c-><c- n>value</c-><c- o>></c-></code>.</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>variant_alternative</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>I</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
</code></pre>
   <p>Let <code class="highlight"><c- n>VA</c-></code> denote <code class="highlight"><c- n>variant_alternative</c-><c- o>&lt;</c-><c- n>I</c-><c- p>,</c-> <c- n>T</c-><c- o>></c-></code> of the <em>cv</em>-unqualified type <code class="highlight"><c- n>T</c-></code>.
  Then each of the two templates shall meet the <code class="highlight"><c- n>TransformationTrait</c-></code> requirements with a member typedef <code class="highlight"><c- n>type</c-></code> that names the following type:</p>
   <ul>
    <li>for the first specialization, <code class="highlight"><c- n>add_volatile_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>, and 
    <li>for the second specialization, <code class="highlight"><c- n>add_cv_t</c-><c- o>&lt;</c-><c- n>VA</c-><c- o>::</c-><c- n>type</c-><c- o>></c-></code>. 
   </ul>
   <h4 class="heading settled" data-level="2.4.3" id="depr.atomics"><span class="secno">2.4.3. </span><span class="content">Atomic operations library [<strong>depr.atomics</strong>]</span><a class="self-link" href="#depr.atomics"></a></h4>
   <p>If an atomic specialization has one of the following overloads, then that
overload is available when <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">false</code>:</p>
<pre class="highlight"><code class="highlight"><c- b><c- b>void</c-></c-> <c- nf><c- nf>store</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>load</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- k><c- k>operator</c-></c-> <c- nf><c- nf>T</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>exchange</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>success</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>failure</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_weak</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- b><c- b>bool</c-></c-> <c- nf><c- nf>compare_exchange_strong</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>expected</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-> <c- k><c- k>operator</c-></c-> <i><c- n><c- n>op</c-></c-></i><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>T</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>T</c-></c-><c- o><c- o>*</c-></c-> <c- nf><c- nf>fetch_</c-></c-><i><c- nf><c- nf>key</c-></c-></i><c- p><c- p>(</c-></c-><c- b><c- b>ptrdiff_t</c-></c-> <c- n><c- n>operand</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>memory_order</c-></c-> <c- n><c- n>order</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>memory_order</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seq_cst</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>volatile</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
   <p>The following non-member function is available when <code class="highlight"><c- n>atomic</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>is_always_lock_free</c-></code> is <code class="highlight">false</code>:</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>class</c-></c-> <c- nc><c- nc>T</c-></c-><c- o><c- o>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>atomic_init</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>volatile</c-></c-> <c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>*</c-></c-> <c- n><c- n>object</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>atomic</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>T</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>value_type</c-></c-> <c- n><c- n>desired</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
</code></pre>
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  <h2 class="no-num no-ref heading settled" id="references"><span class="content">References</span><a class="self-link" href="#references"></a></h2>
  <h3 class="no-num no-ref heading settled" id="informative"><span class="content">Informative References</span><a class="self-link" href="#informative"></a></h3>
  <dl>
   <dt id="biblio-p1152r4">[P1152R4]
   <dd>JF Bastien. <a href="https://wg21.link/P1152R4">Deprecating volatile</a>. 22 July 2019. URL: <a href="https://wg21.link/P1152R4">https://wg21.link/P1152R4</a>
  </dl>